The invention relates generally to containers and apparatus for heating or cooling materials held inside containers. More particularly, the invention provides a can or a similar container for holding a food product or another material, and a self-contained assembly for heating or cooling the container and the material within it to a temperature above or below the material's storage temperature. In a preferred embodiment, a standard metal can holds a quantity of a food or beverage. A jacket or housing surrounds the can, with reagents for an exothermic or endothermic temperature-change reaction inside the jacket in proximity to the can. Activating the device initiates the reaction to heat or cool the can and its contents.
Devices of this general type are known in the art. Some such devices include a food container in proximity to a reagent storage vessel. The reagent storage vessel holds a quantity of calcium oxide and a quantity of water, with a barrier between them to keep the two reagents separated. The devices include some mechanism for breaching the barrier to allow the calcium oxide and water to mix. When this occurs, the resulting exothermic reaction generates heat that is transferred into the food container to raise the temperature of a food product inside the container.
The prior art devices suffer from various deficiencies, though. Some of the devices are prone to leak either steam or heated reactants from the reagent mixture. These devices can be hazardous in use. Concern over the possible injuries to users has severely hindered the acceptability of these devices in the marketplace. Other devices do not adequately control the rate of the reaction after its initiation. The reaction may proceed either too fast or too slow, and too much or too little heat may be transferred to the food. Other devices are overly complex, and difficult, expensive, or time-consuming to manufacture, assemble, use and dispose of. For these reasons and others, there has never been an acceptable mass-market, self-heating product until now.
A need exists, therefore, for self-contained temperature-change container assemblies that are improved in comparison with those of the prior art. Such an assembly should be safe and reliable in use, and easy and inexpensive to manufacture. Container assemblies of this type, and methods for manufacturing in them, are described below in this document.